Calcium-induced environmental adaptability of the blood protein vitronectin
Why this work is in the frame
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Bibliographic record
Abstract
Abstract The adaptability of proteins to their work environments is fundamental for cellular life. Here we describe how the hemopexin-like (HX) domain of the multifunctional blood glycoprotein vitronectin (Vn) binds Ca 2+ to adapt to excursions of temperature and shear stress. Using X-ray crystallography and molecular dynamics (MD) simulations, nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSF), we describe how Ca 2+ and its flexible hydration shell enable the protein to perform conformational changes, that relay beyond the Ca 2+ binding site to alter the number of polar contacts and confer conformational stability. By means of mutagenesis, we identify key residues that cooperate with Ca 2+ to promote protein stability, and we show that Ca 2+ association confers protection against shear stress, a property that provides conformational advantage for proteins that circulate in the vasculature like Vn. The data reveal a mechanism of adaptation. Significance Statement The protein vitronectin (Vn) plays important roles in cell adhesion and migration, bone remodeling and immunity. It circulates in blood, but it is also found in the extracellular matrix, and it accumulates with plaques associated with age-related macular degeneration, Alzheimer’s disease, atherosclerosis and other degenerative disorders. Vn is a calcium-binding protein, and here, we show that calcium helps Vn alter its structure in response to diverse environmental conditions. The results shed light on the way in which Vn adapts to its surroundings. This structural knowledge is important for the development of diagnostic, preventive or therapeutic approaches.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it